First came juice boxes, then fruit roll-ups. Now comes Go-Gurt, which is becoming the next kids’ food fad. Introduced by General Mills in a few markets last fall, the product hit the East Coast in May and will be launched nationally next week, backed by a $10 million ad campaign. Go-Gurt rang up $37 million in sales in its first year despite limited distribution, and it’s expected to become a huge seller in the $1.8 billion yogurt category. In the cutthroat food business, where 12,000 new products are introduced annually but most fail, hits like this are a rarity. The key to its appeal with kids, says General Mills marketer Josh Resnik, is its ability to morph. Eat it refrigerated like regular yogurt, freeze it like a dessert or eat it somewhere in between. Kids rave about flavors like Chill Out Cherry and Rad Raspberry. Another benefit: kids won’t lose all those spoons packed in school lunches.

For marketers, it’s also a reminder of the power of packaging. McDonald’s is a pro in this arena, turning a burger-in-a-box into a Happy Meal. Now tubes are expected to become trendy. “I predict they’re going to be the next wave of snack foods,” says Bob Messenger, editor of Food Trends. He’s already heard about one company tinkering with tubed peanut butter, but he’s hoping for a tubed molten Hershey’s bar.

Parents may cringe at that, but they love feeding kids the new yogurt. Says Tracy McMillan, a California mom who’s buying Go-Gurt for 1-year-old Madelyn: “She thinks she’s eating a Popsicle for breakfast, but it’s better for her.” At least it seems so. But some nutritionists who’ve looked over Go-Gurt’s nutritional information (at NEWSWEEK’s request) say parents should temper their enthusiasm. Dr. Susan Roberts, author of “Feeding Your Children for Lifelong Health,” complains that Go-Gurt has higher fat and less calcium than regular yogurt. Dr. Deborah Chud, a Boston nutritionist, worries all those carbohydrates could make kids hyperactive; traditional yogurt with real fruit mixed in is healthier, she says. But General Mills’ Resnik says that since Go-Gurt competes mainly with traditional kids’ snacks like potato chips and cookies, it’s a far healthier option. Some experts agree. Says Linda Olsen, a dietitian at Children’s Hospital: “It’s a nice way to introduce kids to yogurt.”

So far the kids are enthusiastic. But as with all fads, there’s still a hierarchy of hipness. When a visitor asked those third graders whether Go-Gurt rivals Pokemon in coolness, their faces filled with horror. No way, says one boy: “Pokemon rules.” Around the table, heads bob in agreement.